Pap, also known as Papas (353–374) was a Prince who served as the Roman Client King of Arsacid Armenia from 370 until 374.

Pap was the son born to the Arsacid monarch Arsaces II (Arshak II) and his wife Pharantzem (P'arandzem), who was his third known wife. Prior to his father's Armenian kingship, Arsaces II married an unnamed woman who appeared to have died before the year 358 by whom he had a son called Anob, thus was Pap's older paternal half-brother. The father of Pap served as Roman Client King of Armenia from 350 until 368. Pap is the only known child born to Arsaces II during his Armenian Kingship.

He was born and raised in Armenia and little is known on his early life. Armenian historian of the 5th century Faustus of Byzantium in his writings History of the Armenians (Book IV, Chapter 15), states that the parents of Pap nourished him during his childhood and when he reached puberty he became robust.

Pap was named in honor of Pap, a brief Catholicos in 348 who was Pap's late paternal relative and the first son of Saint Husik. Saint Husik was the grandfather of the Catholicos, St. Nerses I.

Valens was reluctant to bestow a royal title upon Pap in order not to violate an earlier treaty signed by Jovian in July 363.^[5] Valens dispatched his magister peditum praesentalis Arinthaeus to Armenia just as Shapur II invaded the country in pursuit of Pap who was hiding near the Roman frontier in Lazica. Meanwhile, Terentius restored Sauromaces to the throne of Iberia, but the king appointed by the Persians, Aspacures retained control of the eastern part of that kingdom. Instead of going after Pap, Shapur II concentrated his attack on the now long besieged fortress of Artogerassa which fell in the winter of 370, the royal treasure was captured by the Persians and Pharantzem, raped and murdered. Shapur II also began systematically persecuting the local Christians by forcing apostasy to Mazdaism, a form of Orthodox Zoroastrianism.

Shapur II contacted Pap who was still in hiding and tried to persuade him to come over to his side. Under Shapur II's influence Pap murdered the duplicitous Cylaces and Artabanes and sent their heads to the shahanshah as a sign of loyalty. In the spring of 370 Shapur II prepared a massive invasion of Armenia which was realized in the spring of 371. Valens' generals Traianus and Vadomarius met the Persian force in Armenia at Bagrevand not far from the village called Dzirav and came off victorious. Faustus of Byzantium gives considerable credit for the victory to sparapet Mushegh I Mamikonian. Moses of Chorene of Armenia and Roman Ammianus Marcellinus noted that the Valens' generals did not participate in the battle actively but rather were engaged in protecting the King. During the ensuing battles more Armenian territories were reclaimed from the Persians, including Arzanene and Corduene which were ceded to Persians by Jovian in 363.

By the end of the summer Shapur II retreated to his capital at Ctesiphon and Valens went back to Antioch. Shapur II was unable to confront the massive Roman build up in Armenia as a result of his preoccupation with Kushan attacks in the eastern realm of his empire. While peace prevailed with Persia, the situation inside Armenia began to crumble.